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发帖数: 3365 | 1 Pentagon 'Confident' Mystery F-22 Fighter Problem Solved
By LEE FERRAN and LUIS MARTINEZ | ABC News – Tue, Jul 24, 2012 1:53 PM EDT
The military believes it has found the source of the potentially deadly
oxygen problem that has plagued America's most expensive fighter jet, the F-
22 Raptor, for years, Pentagon spokesperson George Little said today.
"I think we have very high confidence that we've identified the issues,"
Little told reporters, before announcing a long-term plan to lift strict
flight restrictions imposed by Defense Secretary Leon Panetta on the $79
billion fleet in May. "This is a very prudent way to ensure that we, in a
very careful manner, resume normal flight operations."
The mystery problem with the F-22 Raptor was the subject of an ABC News "
Nightline" investigation, which found that since 2008, F-22 pilots have
experienced unexplained symptoms of oxygen deprivation -- including
confusion, sluggishness and disorientation -- while at the controls of the $
420 million-a-pop jets on more than two dozen occasions. In one instance, a
pilot became so disoriented that his plane skimmed treetops before he was
able to pull up and save himself. The Air Force subjected the F-22 to
intense scrutiny for years, including a nearly five-month fleet-wide
grounding last year, but was unable to solve the problem. When the grounding
was lifted, the service awarded the plane's manufacturer, defense
contracting giant Lockheed Martin, a nearly $25 million contract in part to
help identify the problem, but still no answer was found.
READ Exclusive: Family Demands Truth in Air Force F-22 Fighter Pilot's Death
The source of the issue, the Pentagon now says, is believed to be a faulty
valve in the high-pressure vest that is worn by the pilots at extreme
altitudes -- one that Air Force officials believe is constricting the pilots
' ability to breathe.
"To correct the supply issue and reduce the incidence of hypoxia-like events
, the Air Force has made two changes to the aircraft's cockpit life support
system," Little said. "First, the Air Force will replace a valve in the
upper pressure garment vest worn by pilots during high-altitude missions.
The valve was causing the vest to inflate and remain inflated under
conditions where it was not designed to do so, thereby causing breathing
problems for some pilots... Second, the Air Force has increased the volume
of air flowing to pilots by removing a filter that was installed to
determine whether there were any contaminants present in the oxygen system.
Oxygen contamination was ruled out."
The Air Force first ordered its pilots to stop wearing the vests last month,
but Air Force spokesperson Lt. Col. Tadd Scholtis told ABC News at the time
that while the vests were believed to have contributed to the problem, they
were "not believed to be the root cause of the prior incidents."
When asked by a reporter if the new solution could also account for the at
least five instances in which the Air Force said ground crews working on the
F-22s experienced their own hypoxia-like symptoms, Little said he "did not
have specifics" on those incidents.
Still, Gen. Charles Lyon, the head of the team investigating the F-22
problem, made his case in the Pentagon against the so-called G-suit and its
valve over the past few days, an Air Force official told ABC News, and
Little said that Friday Air Force Secretary Michael Donley and other top Air
Force officials presented the Air Force analysis to Panetta.
"After receiving assurances that these corrective measures would minimize
hypoxia-like events in the F-22, the secretary approved the Air Force
planned sequence of actions to remove flight restrictions over time," Little
said.
The process starts today, he said, with an order from the Air Force for a
squadron of F-22s to be deployed to Kadena Air Base in Japan. The planes
will fly there at altitudes that will not require pilots to wear the vests.
The Air Force is still in the process of installing an automatic emergency
back-up oxygen system to the planes but that process is not expected to be
completed until next spring.
Despite costing an estimated $79 billion, no jet in the entire F-22 fleet --
some 185 planes -- has ever seen combat. From Iraq to Afghanistan to the no
-fly zone over Libya, the Air Force said the planes simply weren't necessary
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